And yes, tank fire while on the move WAS difficult in WW2, so they only fired their guns at area targets when assaulting, or when the range was VERY close, like under 200m.
Eventhough the Sherman had a stab system, it was not used because it was pretty unaccurate for fire-for-effect.
Basically all WW2 tanks stopped just prior firing since this was the only means to score a hit. Remember they had to judge range too, with a little help of cornering brackets or similar aids in the reticle. The advantage of most german optics were that the gunner could dial up the measured range (via mk1 eyeball though), and aim the reticle center-mass to score a hit, wheras most other tanks had to superelevate the reticle, thus the gun like in AH2 now for all tanks. Its pretty much a Sherman reticle and way of aiming the gun.
Matt